| 摘要 |
PURPOSE:To obtain a high motor efficiency and make the stable high-speed operation of a motor possible at the rated time for normally using the motor. CONSTITUTION:Serially connected two smoothing capacitors C1, C2 are connected in parallel with a rectifier circuit 4 and a switch SW is provided between time connection of rectifier diodes D3, D4 of the rectifier circuit 4 and that of the smoothing capacitors C1, C2. This switch SW is controlled by a control circuit 3, and is turned on at the time of a quick-freezing command being given or a motor 2 exceeding a predetermined number of revolutions and turned off at the time of the rated operation of the motor 2 or the motor 2 falling below the predetermined number of revolutions. When the switch SW is turned off, the rectifier circuit 4 and smoothing capacitors C1, C2 form a full-wave rectification circuit, but when the switch SW is turned on, they form a voltage- doubler rectifier circuit; and the control circuit 3 controls the applied voltage of the motor 2 so that the motor 2 is not placed in an overexcitation state. |
